code: def _rst_underline(text, markup):
      """Add and underline RsT string matching the length of the given string."""
      return text + "\n" + markup * len(text)
  
file_path: datalad/datalad/dochelpers.py
imports: import logging
  import re
  import textwrap
  import os
  import sys
  import traceback
  from datalad.support.exceptions import CapturedException
label_desc: Use image node_id 2 for calling a global function with example usage: _rst_underline(text, markup) and returns: unknown